90 [April 6, 
Lockington.] 
same species of trout attains a larger size in large rivers than in small 
streams ; anadromous salmon of a large species have, when by accident con- 
fined within a small fresh-water lake, in a few years so altered, becoming 
sexually mature when quite small, that a naturalist who did not know the 
cause might take them for a new species ; fishes confined within a space so 
narrow that normal growth was impossible, yet supplied with food, have 
grown to fit the space ; the clear silvery tints and graceful forms of salmon 
when in the sea are so unlike the muddy colors and misshapen outlines 
presented by the same individuals after ascent of a river that observers 
have founded on them many false species; and the larva of the conger 
eel becomes at times converted into a transparent, colorless pelagic fish 
that has received the name of Leptocephalus Morristi. 
Is it not reasonable to suppose that the outline of a plastic atom of pro- 
toplasm, bounded only by a delicate pellicle, is more readily amenable to 
the influences surrounding it than that of the million-celled creatures 
which are known to change so greatly? 
The vegetable kingdom offers examples of variation as striking as those 
of the animal. 
It is as hard to find two leaves of the same plant exactly alike as it is to 
find two Dromios. The stem-leaves and root-leaves of the same herba- 
ceous plant differ more from each other than from the corresponding 
leaves of a kindred species. In some trees, as the ivy and the mulberry, 
the play of form is so great, that one unacquainted with the facts would 
certainly believe that forms gathered from the same stem belonged to dif- 
ferent species. Hach leaf, as truly as each human being, has its own par- 
ticular environment, its share of light, heat, nutrition, etc., and these 
work changes in its form. 
The change effected by the environment upon a plant goes further than. 
form, size, or color, and extends to the nature of its secretions, so that 
plants which, when grown under certain conditions, are good food for man 
and. beast, become toxic under other conditions. This is true of many of 
our garden vegetables; and, to come nearer to our microscopic organisms, 
it is true of certain many-celled fungi, such as the common agaric of the 
meadows. ‘ 
In the latter case the fungus is on all hands allowed to be the same, yet 
while one specimen it innocuous, another is toxic. 
Would it be very remarkable if it should be proved that an innocent 
one-celled microbe, surrounded with diseased and poisonous pabulum, 
should, if able to resist the influences around it without perishing, become 
poisonous itself ? 
Against the usual form of the germ theory, with its specific germs in- 
ducing specific diseases, it is allowable to put forth the following : 
The microbes that swarm within the body of the victim of a eymotic disease, 
are either the lineal descendants of those which inhabited the same body when 
én health, or are the lineal descendants of those which once dwelt in some other 
